Bending the sides
Bending irons to the left is an antique violin makers iron heated by a spirit lamp. In the middle is a modern electric iron and at the right is an iron made of three inch diameter pipe squeezed in the vise to an oval eight inches back from the end faceing you with a movable end cap for heat control. The pipe has a hole cut at the dark area in the image for heat from a gas burner to enter, at each side of the hole are fixed iron bars for clamping to the stove. The end of the pipe is capped. Pipe is also used to make vertical bending irons they are about a foot tall,capped on the bottom with legs. They are heated with charcoal,cotton or rags soaked in alcohol or kerosene provide heat. The electric iron is safer and emits no fumes.